We are evaluating the effectiveness of an antimetabolic agent, termed "antabalone", found in the brains of hibernating ground squirrels, (Citellus Tridecemlineatus), in limiting myocardial damage due to hypoxia. Work is presently in progress in two areas. An isolated rat heart preparation is being employed to determine antabalone action on myocardium. In addition, both cell culture and whole animal assay systems are being evaluated so that purification and concentration of antabalone can be made.